Hiking for an Old Man

Discussion in 'Sunfish Talk' started by sjs, Sep 12, 2010.

  1. winever

    winever Member

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    Thank you WD, and I should prolly raise the board too...DUH. It's not in my mind to think about how to fall over. LOL, Winever.
     
  2. Fred P

    Fred P Member

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    Wavedancer:
    This is from the Wikipedia entry on "Sailing":

    "If a sailing vessel heels too much, the real solution is to reduce the sail area, by removing and/or reefing sails. Raising the centreboard can reduce heeling, which can be surprising, but it is not an ideal solution as it only works by increasing leeway."

    This is what I always understood. There's less rotational (heeling) force on the dagger if there's less area preventing leeway.

    Fred

    P/S. Here's the Wikipedia entry from "Heeling":

    "One way to reduce heeling is to move the center of lateral resistance upwards by raising your centerboard or daggerboard. The boat will have less resistance below the waterline and consequently less heel."
     
  3. billmcinnis

    billmcinnis Member

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    I’m 71 and I sail in 15-17 regattas a year plus frostbiting and club sailing. In my opinion you’d be hard pressed to find a more stable dinghy type boat. You have to work a bit upwind in heavier breezes, but as others have said, the jens makes it a lot easier. As far as capsizing goes, with most boats the problem is downwind not upwind. With the Sunfish sailing downwind in a breeze is a piece of cake.
     
  4. ylojelo

    ylojelo Member

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    I doubt having the daggerboard down will effect your intended capsize, but you will want it down in order to flip the boat upright.
     
  5. Wayne

    Wayne Member Emeritus

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    All true..., but you may recall I brought up "threshold". If the energy of wind in the sail were concentrated at the waterline, then lateral drift would be the only concern. Unfortunately, the force is not channeled to that ideal region. The wind in the sail also creates a rotational force aloft…, the leverage commensurate to the height and size of the sail. When the force in the sail exceeds the sideslip freedom you get dumped … fast.

    The physics of leeway is not universal up the entire scale…, reach the threshold, go swimming … it’s one of those self-correcting issues.

    .
     
  6. Fred P

    Fred P Member

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    Wayne is correct. Raising the board a little will not prevent heel/capsize, just reduce the involved forces somewhat. With the board not fully down, the wind force on the lower, larger part of the sail close to the higher center of lateral resistance will produce less heeling torque and more leeway. The upper part of the sail can still produce enough rotation to put you in the drink.

    Fred
     
  7. Light and Variable Winds

    Light and Variable Winds Well-Known Member

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    I think I have a handle on this, but let me pose a question regarding an "imminent capsize":

    Suppose I have a device that automatically adjusts the daggerboard [upwards] when it senses an "imminent capsize". :cool:

    Why wouldn't that device delay or prevent a capsize? :confused:

    Besides "sailing inefficiently", why isn't sailing with a board routinely raised four inches going to accomplish the same thing? :confused:

    (I'm not getting any younger, and the water is getting colder now!) ;)
     
  8. Fred P

    Fred P Member

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    I'm sure you'll get more responses but here's my two cents:

    Even having the board completely up will not prevent a capsize because of the hull's resistance in the water which will allow the force on the sail to rotate the hull into a capsize.

    Moving the board up might prevent an imminent capsize if it's not too severe.
    In my experience, a severe capsize happens very quickly and leaves no time for any adjustments except holding your nose for the dive. When a capsize is slowly imminent you will have lots of side pressure on the board and it will be pretty hard to move, especially if your heeled over.
    That's why I recommended keeping the board up a little all the time to at least reduce the possibility of capsize but it won't eliminate it.

    Fred
     
  9. Wayne

    Wayne Member Emeritus

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    That's the physics of the situation in a nutshell..., unless you can levitate the hull for zero lateral resistance. ;)


    IMHO it's much less work to just sail the boat skillfully, applying normal capsize abatement tactics like letting out the sail and/or briefly turning into the wind, rather than fiddling with the ragged edge of the capsize moment equation ... a constantly moving target ... by futzing with the least effective control element, the daggerboard.

    The real "Easy Button" is to simply get enough experience so that sailing fundamentals become second nature.

    .
     
  10. Wayne

    Wayne Member Emeritus

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    Or you could have outriggers that spring out, or perminant outriggers for that matter.

    What some people have already done with the sailboat design is to make the daggerboard a fixed element and they even add counter-balancing weight.

    There's no limit to what might be done...

    [​IMG]

    ;)
     
  11. Wavedancer

    Wavedancer Upside down? Staff Member

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    Thanks Wayne for pointing out the fundamentals.

    As an aside, it's been my experience that a capsize to leeward, while sailing upwind, is pretty slow, NOT fast. In most cases, I should have been able to prevent capsizing by anticipating the coming gust, releasing the sheet in a more timely manner, and by hiking harder at the proper time. However, I am not twenty anymore :eek:, and never had the agility of top sailors. Hence, I do swim from time to time. Moreover, I rarely get to practice in mid-twenty breezes.

    The other chapter relates to 'death rolls' going down wind or 'stuffing' the boat in a wave while surfing. These situations can lead to capsizes that happen faster. I have also capsized by being stupid enough to leave the board up a bit too much during a jibe in high winds (as a racer, I carry the boom low).

    Finally, if the board was up for one reason or another prior to the capsize, the first thing to do, after getting free of the boat and lines, is to extend the board for full leverage.
     
  12. Wayne

    Wayne Member Emeritus

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    Heck, did you watch the 470s in the final round of the Beijiing Olympics..., they all capsized at least once. Dinghy sailing is like that some days. So you go out and brave the wind anyway or go home and mow the lawn. I go sailing (which includes an occasional swim).

    .
     
  13. Light and Variable Winds

    Light and Variable Winds Well-Known Member

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    You're writing to a former catamaran sailor. ;)

    :confused:

    I think I may be "being made fun of", but I can't be certain. :p
     
  14. Wayne

    Wayne Member Emeritus

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    :eek: OK, let's have a look a the practical side... What would this system need in order to function successfully? Would this be a mouse trap device or fly-by-wire technology?

    Which brings up another question..., why wasn't the daggerboard simply shortened years ago to create the capsize proof boat?


    [​IMG]

    .
     
  15. baseman

    baseman On the Water

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    I think I might be missing something in the logic behind using the daggerboard to minimize the possibility of a capsize. The daggerboard is quite small in relation to the size of the boat, and doesn't provide anything in the way of ballast. By the time you get the boat heeled far enough to where a capsize is almost certain, how much of the daggerboard is still in the water? And at that point can you really think of doing anything but letting go of the sheet and the tilller and preparing yourself for a swim?

    The only way I know to keep the boat from going over is to depower the sail. The best way to maintain boat speed is to keep the boat as flat as possible. If you can't hike it flat, ease the main.

    I'm not 20 anymore either, but I'm small and have always been fairly agile, but I still prefer to keep the boat upright. I've been racing my Phantom for 2 years and haven't been knocked down yet.

    <end ramble> :)
     
  16. Light and Variable Winds

    Light and Variable Winds Well-Known Member

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    Re: Hiking for an Old Man—You asked!

    I wasn't really thinking in practical terms—just using a "fer-instance". ;)

    But, since it is too cold for sailing today, I'll address your questions:

    1) Setting the daggerboard aside, the Sunfish has little built-in resistance to making undesireable leeway—it has some resistance—but given reasonable weather for sailing, not enough to develop a capsizable circumstance.

    IMHO.

    A capsize-proof boat in Sunfish-sizes doesn't exist: Other sailboats either capsize and/or sink.

    2) "Mousetrap" is simpler, but I propose telemetry: build goggles that can measure—give them wireless capability—and do real-time viewing of the skipper's eyes. :cool:

    When the skipper's eyes get very, very, wide, a signal will be sent to a 12-V servo-motor, which—coupled to a worm-drive and a pinion—will rapidly raise the daggerboard.


    Capsize averted!

    :)
     
  17. baseman

    baseman On the Water

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    Re: Hiking for an Old Man—You asked!

    In that case, a voice activated system would work as well.

    Oh (insert your favorite word here)
     
  18. Wayne

    Wayne Member Emeritus

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    …you’re catching on, but it’s all been very entertaining. :eek:

    Theoretically it should work, but in a very narrow band of wind and water conditions…, not to mention learning the recognition of and practicing the reaction to will likely equal or exceed the effort of just learning Sunfish sailing basics.


    Yes, but remember the medium it functions in is quite “dense” by comparison to what the sail operates in.


    OK…, next time you are out give it a test. Pull up the board and see what results you get at different wind speeds. I will anxiously await your report on if a capsize moment transition point may or may not exist. ;)


    Good Idea(s)

    I think I will link those reaction sensors to a pair of air bags I’ll embed in the gunwales. :p

    ... oh, and one in the spar top ... just in case. :rolleyes:


    :D
     
  19. baseman

    baseman On the Water

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    Sometimes, not even having pontoons can save you.
     

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  20. Fred P

    Fred P Member

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    Wayne, your cowboy is a gem!

    Fred
     

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